Pressure sensors have been fabricated for operation over a broad range of environmental conditions. In such sensors, piezoresistors coupled to a diaphragm may be used to measure a pressure. The piezoresistors may be conventionally arranged as a Wheatstone bridge. Upon the application of pressure, the sensor's diaphragm deflects slightly which induces strain onto the piezoresistors. The piezoresistors respond to this strain by a change of resistance. The Wheatstone bridge configuration typically includes four piezoresistors that are arranged on the diaphragm such that two piezoresistors are put in tension while the other two piezoresistors are placed in compression. This way, two piezoresistors increase in value, while the other two piezoresistors decrease in value by the same or similar amount. By connecting the piezoresistors under tension on opposite arms of the Wheatstone bridge, and by similarly connecting the piezoresistors under compression on the other opposite arms of the Wheatstone bridge, the output of the Wheatstone bridge can produce a voltage which is proportional to the applied pressure. For high temperature operations, as indicated, the diaphragm may be a metal diaphragm. For example, see U.S. Pat. No. 7,733,209 to Kurtz et al, entitled “High Temperature Pressure Transducer Employing Metal Diaphragm,” filed Jun. 15, 2006, and assigned to Kulite Semiconductor Products, Inc., the assignee herein. The specification of said U.S. Pat. No. 7,733,209 describes a sensor utilizing a metal diaphragm and piezoresistors, with a ratio known as the transducer sensitivity given by the following equation:
      S    =                  1        P            ⁢                        V          out                          V          B                      ,
where S is sensitivity, P is applied pressure, VOUT is output voltage, and VB is voltage applied to the bridge.
It is highly desirable that the output of the pressure sensor is sensitive only to pressure and is not affected by other environmental factors. A notable factor is temperature and therefore the sensitivity of the pressure sensor should be independent of temperature. Many factors affect the sensitivity of a particular sensor, including geometric, physical, and electrical factors. Unfortunately some of these factors are indeed temperature dependant which leads directly to temperature variation in the sensitivity. Various schemes must then be utilized to minimize this temperature variation of the sensitivity. These schemes are collectively known as temperature compensation. As one will ascertain, the prior art is replete with a number of temperature compensation methods. See for example U.S. Pat. No. 6,877,379 issued on Apr. 12, 2005 and entitled Doubly Compensated Pressure Transducer issued to Dr. Anthony D. Kurtz et al and assigned to the assignee herein. That patent describes a compensated pressure transducer which has coarse and fine temperature compensation. See also U.S. Pat. No. 6,700,473 issued on Mar. 2, 2004 entitled Pressure Transducer Employing On-Chip Resistor Compensation to Dr. Anthony D. Kurtz, et al and assigned to the assignee herein. That patent describes a technique for compensating temperature in a pressure sensor. Thus, as one will ascertain, there are many techniques described in the prior art to provide compensation of pressure sensors for temperature. However there still exists a need for improved temperature compensation in pressure sensors.